ECO probably sold very few of these Islanders with the cash box on them. In almost 30 years of messing with ECOs, I have only owned one, and have heard of one other, your's makes it three. If your's is complete, it is probably worth 2-3 times what the "Air-Water" sign you put on your unit.

Jack

Author, 1st & 2nd editions of Gas Pump ID book, 3rd edition is now available at www.gaspumpbible.com
Air Meter ID book also available